How to help keep birds from flying into windows
Despite having brains with an intellectual capacity comparable to a chimpanzee, songbirds cannot tell the difference between a mirror image and the real thing.
That’s why a male mockingbird attacks the side mirror on a car, thinking the image is another mockingbird intruding on his breeding territory. Same thing with a male cardinal pecking on a window of your house.
A songbird’s brain stores a mind-boggling vocabulary of songs, whistles and chirps. A male mockingbird can mix and match melodies from a repertoire of up to 200 different songs. A Carolina wren can do the same with a repertoire of about 40 songs.
And that’s not including an unbelievable lexicon of whistles and chirps.
Songbirds learn and master a complex language of songs much the way we learn to speak. That means songbirds have to learn songs from their parents and kin.
But if songbirds are so smart, why can’t they see mirrored images? It’s because they never learn about mirrors, whereas newborn children take 18 months to two years to learn about mirrors.
Perhaps birds will learn about mirrored images one day, although research on teaching birds to recognize themselves in mirrors has been inconclusive. Meanwhile, birds will fly into windowpanes, often to their demise, because they perceive the mirrored image of trees, plants and the sky as the great outdoors.
Before World War II, birds didn’t usually see mirrored images in windowpanes. But after the war, manufacturers introduced plate glass with a smooth finish for installation as “picture windows”
in homes. Similar glass became popular on high-rise office buildings.
The physics of light explains that smooth, shiny surfaces like a windowpane or the chrome on a car bumper refract light to create a mirror image of the surroundings. Birds see those mirrored surroundings as a real-life scene.
Nor can birds see clear glass. We can’t either, but we learn to be aware of clear glass, except when we absentmindedly bang into a glass wall. Songbirds crash into glass windows that look like a clear flight path.
But songbirds beat us at color perception. They see the ultraviolet spectrum we can’t see, and we’re virtually colorblind compared to a bird’s vision of blues, greens and reds. It’s why a female cardinal sees much richer shades of red on a male than we’ll ever see.